Method of and apparatus for controlling mechanical oscillations



June 9, 1931. P. B. SAMPLE 1,809,283

METHOD UP AND APPARATUS FOR CONTROLLING MECHANICAL OSCILLATIONS Filed NOV. 12, 1929 P j lNeENToR ATTORNEY duce a roll or oscillation in a vessel in a" Patented June 9, 1931 1 UNITED ESTA PERRY IB. SAMPLE, or new Yonir, N. Y., ASSIGNOR or ONE-FOURTH TO iRA J. ADAMS- ms) PATE Temet- METHOD or AND APPARATUS non ooivrRoLLIivG MECHANICAL-OSCILLA'IIONS 5 p Application filed November 12, iezafseriai No. 406,763..

This invention relates to methods of and apparatus for controlling mechanicaloscillations and moreparticularly oscillations of ships produced by waves.

One object of the invention is to oppose the oscillating forces setup in an object by external forces and keep the object ina I state of equilibrium.

. Another object of the inventionis to re duce the roll or oscillation'of a vessel to a predetermined point to permit the firing of guns at the desired angle of elevation.

Another object of the inventionis to pro-,

calm sea to permit the desired elevation of guns to be fired at the enemy,

1 Other objects will appear in the following description, reference being had to the drawing in which'the singlefigure of the drawing is an illustration and gives conventional circuits andassoclated devices to carry out the principles'of the invention.

The waves of the sea cause ships to roll in substantial synchronism therewith. In most cases this roll is decidedly objectionable and various attempts have been made to balance or stabilize the vessel against the out of the plane of rotation. However, when a gyroscope has once been turned out forces of these waves. In some cases gyroscopes have been used on ships to prevent the roll of the vessel due to the inherent resistance of a rotating bodyto be deflected of its plane of rotation it will offer no furs ther force to get baokinto its original plane ofoscillation but will be stable in the new plane to which it has been moved.

In m iinventionthere is: a continual force actlng to return. the vessel to its r-original pos1t1on, there being substantially only one plane inwhich the stabilizing forces will cease to act on the vesseland this is when the deck is in the horizontal plane. Y

To produce the stabilizing forces Imount' two .dynamo electric machines 1, 2, on the ship with the shafts'3,4, of the armaturesj extending parallel to the length ofthe ship and secured to flywheels i5 and 6. These dynamoelectric machines in acalm sea with] avessel in equilibrium are designed to run as motors and are so connected that the armatures rotate the flywheels in opposite The motors w ll run at a su'bstantiallyifconstant speed when the vessel is'stable in a directions asindicated by the-arrows in thedrawing.

calm sea and thereaction of the fieldfframes (not shown) resting on the deck of the the field frames against the vesselwould be slight because the motors would be running idle and there would be verylittle torque between the field andthe armature through I the magnetic flux.

If, however, the vesselis :caused to' the field of one'of these motors and to weak; en the field of, the other} This will cause the firstmotor to act as afgenerator, the driving by thewaves means is provided'tostrengthen."

force being the kinetic energy of flywheel 6."

Theother motor will continue to actas a motor, but since its field is weakened it will speedup in accordance with wellkn'own principles. The reaction of the: generator 2 is in the direction ofirotation' of the'fiyactionof the field frame in the motor 1' .opposite to the direction of rotation-of the flywheel 5, or counter-clockwise; Therefore,

' wheel, i that is, counterclockwise, and the refields of'the'two dynamo electric machines 1 have been changedin the way described reaction of their field frames iwill" both be counter-clockwise,that is,the field.

frame will attempt to turn the vessel court'- 1 a ter-clockWis'eL For stabilizing vessels the: connections to the motors are so madethat this counter force of the: field frames is j opposed to the direction of roll offthevessel produced by the waves'andthe counter force 1 "of the field frames can bemade as great as desired-by appropriately designing {the fly- 7 wheels and the electrical control apparatus. q:

The manner in which the foregoing effects are produced will now be described in detail.

To start the .dynamo electric machines starter switch S -will be in the position shown and for the present we will assume that battery switch SE is open and switches SR and SI are closed, as illustrated in the drawing. Current will then flow from main L1 through the starter arm, contact 7, wire 8, field 9,wires 10, 11, back to main L2. Current will also flow through the starter arm in contact strip ,8, wire 12, to field 13 and wire 11 back to the main L2. The full potential of the line will be thrown on fields at this time to give a heavy starting torque. Current will flow to the armatures of the dynamo electric machines from main L1, the arm of the starter switch, through starting resistance 14 to junction point ment of the armeof the starter switch S to cut out resistance 14 at the desired rate the motors will be brought up to speed.

Now, let it be supposed that the-vessel is caused to roll by the waves. When the Vessel rolls through a small angle bar 23 the pendulum'switch will move with the vessel through the frictional contact between the bar and a pin 24 fastened to the switchboard supported by the Vessel. Bar. 25 will not move because it is fastened to pendulum weight 26 which tends to hold its position on the supporting pivot'27. This will bring the contacts 28 and 29into engagement and as the vessel rolls still further bar 23 Willi remain stationary on account of the engagement of thecontacts 28 and 29. The. f ictional contact between pin or pivot 24and the bar 23 permits this. This frictional contact may be controlled by means of the tensioning springs 30, 31, which may be adjusted-by appropriate means such as the f screws shownin the drawing. The bringing of contacts 28 and 29 together causes current to flow from main L3, rheostat 32, short circuiting contacts around resistance 33 res sistance 34, the right-hand side 36 of the Y potentiometer wire 37 to contact '29, thence to contact .28, wire 38 reversing switch through cross connection 40, through the reversingswitch 41 by way of bar 42 to,

wire 43, coil 44, coil 46, wire 47 and thence to main L4. I V i It will be noted that coil 48 above coil 44 is energized because it is connected in parallel to resistance 21 in the armature was in equilibrium.

circuit of dynamo electric machine 2. At

this time the direction of current in coil 48 contacts 51 and 52 together to short-circuit resistance 53, placed. in the field circuit of dynamo el ctric machine 2 when the starter switch was moved to full running position and opening the continuity between contact strips 7 and 8.

The short-circuiting of resistance 53 increases the current flowing through field 13. The increase of flux through field. 13, however, is retarded by short-circuiting coil 54 on account of the current induced therein. As soon as the current becomes steady the field shortcircuiting coil 54 will draw no further current. The short-circuiting coil 54 thus tends to smooth out the field current surges and by doing this it minimizes the sparking at the switch contacts 51 and 52. It also keeps down'the sparking at the commutator of the machine. This increase of current in field 13 converts dynamo electric machine 2 into a generator because with that field strength the machine is running above the correspondingspeed as a motor. The kinetic energy of flywheel 6 drives the armature forward in the same direction and feeds current into. the armature of motor 1.

When contacts 28 and 29 of the pendulum switch are brought together coil 46 is energized, as already explained. There is no current in coil 55 acting on the core fastened to switch bar 56 and the current in coil 57 shunted around resistance 17 is insufiicient to overcome the tension of spring 58. Therefore, contacts 59 and 60 associated with switch arm 56 remain open for a longer length. of time than when the V6SBl This correspondingly weakens the field of dynamo macnine l and causes .it to speed up as a motor. In doing this it will draw a heavy armature current in order to accelerate the heavy flywheel 5. This heavy armature cu rrent is vn from the armature of dynamo electric machine 2 nowrunning'as a generator but some cur rent is drawn from the mains L1 and L2 to make up for lossesin the'machines and the differential action on the machines due to the rolling of the vessel. W hen the vessel is rolling it partially rotates by the amount of the angle of the r ll, the field frames of each machine. This partial rotation of the field of the generator'reduces to a small extent the current generated therein and it lncreases the current n the motor for a sim ilar reason. The mains lave to make up thisrdifferenceon the load of the twoma chines due to the rolling of the vessel.

Roughly speaking, the total'diflerence between the loadof the machine running a motor and the one running-as a generator: should be less than 15% of the whole load, the 85%' being iurnishedaby the retarded the flywheels, the tensioning of springs and 58, and otherwise proportioning the various constants in the circuits, the reacting force of the field frames may be made tocounteract theroll of the vessel produced by the wavesand maintain the ship' in equilibrium;

The regulating switches associated with bars 49 and 56 will cause the current through,

the armatures and machines 1 and 2 tov be substantially constant, or if desired, to increase or. decrease duringithe stabilizing action. I When the. machine 2 is operating as a generator the current through coil 48 will be in a direction oppositeto the direction of flow of the current whenlthe sameunachine is operatlng as a moto'r. Therefore,

' when this current increases to a predetermined extent it will oppose the flux of .coil

44 sufiiciently toperinitthe spring. 50 to open thevcontacts 51 'and'52 and' reinsert resistance 53 in the field circuit. -This will will decrease the acceleration ofmachineh reduce the armaturev current and. when. it drops below a predetermined point the tension of spring 50 willagain be overcome by the. prepondering flux of coil 44 o'verthat of coil 48. In this wayiswitch bar 49 will oscillate around its pivot point 61 to open and close contacts 51 and 52 at a sufficient rate to keep the desired current flowing through armature .2. As has, been stated,

this-current may be maintained constant as the energy is absorbedirom flywheel 6, or it may be made to increase or to have anyother desired value. In practice I prefer to keep the current substantially constant.

1 The current flowing through armature 1 will likewisebe maintained at the desired value by the action of coils 57, i6 and spring 58. If machine 1 tends to speed up'too rapidly and draw too'heavy an armature cur-' rent the drop in resistance 17 willbe suiiicient to produce a flux in coil" 57 that will overcome the pull of coil 46 and spring 58 and bring, contacts 59 and 60 together;

When this happens resistance 60 in the circuit of field 9v will be short-circuited. This which isrunning as a motor. Contact. 59 will therefore 'fioat up and down through] the action of the coils and spring in the same way as in contact 51 on, bar 49 and'maintain' V I r 70. foroes tend to roll the vessel in the opposite direction bar 28 will move with the vessel and open contacts 28 and 29 on the pendulum SWlliCh." This the desired current flowing through the armature of machine 1.

i If the waves or other will deenergi'ze coils i-land 46 of the current regulator of the dynamo electric machines; At substantially the same time contact '61 of the pendulum switch will be brought into engagement with the contact 62. This will cause current to flow through left-hand end 63 of the potentiometer through contact 62,

contact 61, connection 630i reversing switch 39, bar or of reversing; switch 41,-wire65,

coil 55, coil 66, wire 47, back tothe mains.

At this time :the energization of coil 66 "will aid the spring 50 to overcome the pull of co1ll8 (coil eat at this time being deenerg1zed) and separate the vibrating contacts 51 and 52 for greaterperiods of time. The

energization of coil 55 will produce a flux that will aid the flux ofcoil 57 to overcome the tension of spring 58 (coil 46 at this time being deenerg'ized): which will rotate bar 56 1 around its pivot point 67 and bring vibrat ing contacts 59 and 60 together "for greater periods oftime. I

, The effect of bars'56, 49 is toweaken the field of machine 2 by maintaining theshunt aroundfield resistance 53 openfor greater periods of time. andto strengthen the field of ma'chine'l' by short-circuit resistance 6O for greater periods of tnnei This will convert machine v 2 into a motor and machine 1 into a generator. The reactionof thefield' frames ofthese two machines on the vessel will beinthe same direction but the direction will be this conjoined action'of the" reversedto that previously considered. In

other words, the reaction of bothfield" frames will be against thewforce tending to roll the vessel. As before, the current in the armatures of the motor 2 and generator 1 will be -maintained-at the desired value by the regulator bars 49 and 56 to bala-ncethe :torceoi the roll and keep the vessel'in equilibrium; i The correct value of current in mentof the tension of springs 50 and 58, as already referred to. f V

Sudden. changes of flux in thetfield coil 9 are opposed by the counter fluX'set up in short-circuiting coil 68, the action being :the

same as that of coil 54 already described.

The adjustment ofthe currents in the'dynamo electric machines and; therefore the; value of the reactlng force may likewise be controlled by adjustment of J the resistance in rheostat 32 andthe; balance between the machines 1' and 2 maybe further controlled thesemachines may be obtained by adjust .kept in vibratory action by means of cam 71 contacting with the ends of bars 72 and 7 3 pivoted at 74 and 7 5 on the opposite ends of which bars the contacts are secured. Cam 71 is rotated by any appropriate means such as by a small shunt motor 7 6 connected across the means L1, L2. These contacts 52 and may be floated up and down by any other appropriate means.

The regulator bars 49' and 67- are caused to have steady motion up and down under action of the pulling forces by connection to dashpots 77, 78, designed to yieldingly oppose movement of the bar in either direction. Such dashpots are wellknown in the art, but it may be generally said that this action may be obtained by having a bypass around from one side of the cylinder to the other with an adjustable restriction in the bypass to control the movement of the oil or other fluid forced one'way or the other by the movable piston.

With the arrangement described one may so proportion the armature currents of the dynamo electric machines as to produce the desired reacting force to balance out the opposingforce in any object that is subject to mechanical oscillations. 7

The arrangement also may be used to produce desired oscilfilations in an object insteadv of opposing undesired oscillations.

One instance where it is desirable to produce such oscillations 1s in a war vessel on a calm sea or when there 1s lnsufiiclent roll of the vessel to permit the guns being fired at the desired angle of elevation. The manner in which these oscillations may be generated or produced 'in an object, for example, a vessel, will now be described.

Suppose the vessel is'in a moderate sea and it is desired to roll the vessel, say 10 in order to obtain the desired elevation of the guns at the maximum amplitude of oscillation. 1 Hand reversing switch 39 would be thrown to the left-hand position as shown in the drawing and regulator 7 9 of the pendulum control switch would be set to 10 on the scale. Through link 80 connected to bell crank 79 and bar 81 pivoted at 82, contact 89 would be raised tothe desired position through link 84, bell crank 85 and link 86.

The lever 87 pivoted at 88 would raise contact 89 to the desired position. At this time,- it is preferable to cut out the resistance in rheostat 32 so that there will be maximum pull of the coils 44 or 55, as the case may be, in the current regulators. As soon as rheostat .32 may be cut back into the circuit as may be necessary.

The circuit through contacts 28 and 29 of the pendulum switch previously described would now pass through coil 55 and coil 66 instead of coil 44 and coil 46. Also the circuit through contacts 61 and 62 previously described would pass through coils 44 and 46 instead of coils 55 and 66 as previously described. This means that when the vessel rolls slightly in a moderate sea and contacts 28 and 29 or 61 and 62 are brought together the reacting force of the field frames of machines 1 and 2 will be in the same direction as the force of the roll. Instead of stabilizing the vessel regulator will in,-

, crease the roll. The circuits in this situation need not be traced as they will be the same as already described except that the reversing switch 39 will reverse the action as just referred to.

The desired roll of the vessel may be produced by regulating hand rheostat 82 to adjust the pull on the regulator bars 49 and 56 and thereby control the armature current in the machines 1 and 2. It, of course, would be difiicult to exactly maintain the desired roll by means of rheostat 32 so that it should be set to maintain more than the maximum roll or 10. Suppose that the vessel is rollmg so as to bring contact 28 into engagement with contact 29 of the pendulum switch. This would convert machine 1 into a generator, slow down thefiywheel 5 and speed machine 2 up as a motor to accelerate fivwheel 6 and the reaction as described would aid the roll of the vessel.

When the vessel reaches the desired angle of roll, say 10, the engagement of contact 29 with contact 28 will prevent further movement of bar 23 and the vessel would rotate the supporting pivot 24 in'the fric-' tional bearing of that bar.

82 and the regulator 79 and crank levers are secured to a panel board supported by the vessel. Therefore, as the vessel continues to roll slightly beyond 10 there is relative movement between contact 89 on bar 87 and upper contact 90 on the left-hand end of bar 23. These two contacts will therefore be brought together. This will close the circuit from main L3 to solenoid coil 91, solenoid coil 92, wire 93, solenoid coil 94, switch 95, wire 96, contact 89, contact 90, wire 97, back to main L4. This will short-circuit the resistance of rheostat 32 by energization of coil 91 and it will Pivots 88 and associate bell energize coil 92. The closing of this circuit verse the action by deenergizingcoils. 55 c and 66 and sending the current through coils 44 and 46. This will convert machine 2 into a generator and machine linto a motor and the reaction of their field frames will'now oppose the roll of the vessel arresting it substantially at the -10 angle set by control device 79. When the ship starts the return roll contacts 89 and 90will be open. This deenergizes coils 91,. 92 and 94. The deenergi'zation of coil 94: permits spring 98 to snap the reversing switch 41 ,back' into the right-hand position. As the vessel starts the return roll contacts 89 and 90 will open prior to the opening of contacts 28 and29 because of the action of spring pressed pin 99. This insures that contacts 89 and 90 open before contacts 28 and 29. 7

Prior to the reversal solenoid coil 92 had opened the shunt around theresistance 33. This switch is connected to a dashpot that permits free upward movement of the switch as shown in the drawing, but restricts its downward movement such as by a bypass with a ball or other valve (not shown), as well understood in the art. This inserts resistance 33 in the control circuit' and keeps it there for several rolling cycles and thus reduces the tendency of the apparatus-to roll thevessel, and tending to prevent its rolling the vessel beyond the 10 angle in succeeding oscillations until th'e switch drops back into position and again short-circuits resistance 33. At that time the system will operate with its former, set rolling force again. The length of time that the resistance 33 remains-in .circuit' can be controlled by appropriate, adjustment of the bypass in the dashpot. I

If instead of a moderate seathere is a heavy sea running that" rolls the war vessel, for example, to 15 and it is desired to reduce this roll to 10 for firing guns, switch 95 would then be placed against contact 100, placing resistance 101 .in the circuit of coil 91 and coil 102. This movement or switch 95 opens the circuit of coil 94 on'the, reversing. switch 41, but no current is flowing through. .The rolling of the vessel would be opposedby the dynamo electric machines 1 and 2 through closing of say, contacts'28 and 29 and thenew position of reversing switch 39 in a manner. that was first described, but rheostat 32 would be regulated so as not to reduce this roll to zero, but to let the roll exceed somewhatlthe desired 10. When the roll exceeds 10, assumingthat the vessel is rotatingcontacts 28 to the left, as shown in the drawing, bar 23 will remain stationary as; soon as contact 28 engages contact 29. Further movement of the vessel will cause this bar to sliponi its pivot24. Lever 87 andits attached contact 89 will roll with the vessel,-however, and contact 89 will be brought jinto engagement. with This will close the circuit ontact 90 soon aftergthe 10. angle is passed.

7 rom coil 91 through coil 102, resistance 101, -switch.9 5, contacts 89 and 90, back to'main L4. This will energize coils102, 91,.and short-circuit resistances 3 1 and 32, increasing the current flowing through the; control rheostatcircuit As has previously been pointed outthis increase of current w1ll malntaln a stronger.

stabilizing action on regulating switchbars 49 and 56, thus keeping the roll down to the desired 10. 1 I The switch controlled bycoil 102is preferably attached to a dashpot that will'permit quick upper movement, as shown; on the drawing, but slow downward movement.

As the plunger is forcednpward it com' presses contacts 103aga1nst thelr spr ngs;

Then as the switch plunger moves slowly downward against the retarding action of the dashpot these contacts 103 will recede downward and maintain the shunt around.

resistance '34. The dashpot will preferably be adjusted to make this short-circuit for one or more cycles, or even more, of the roll of the vessel, and this adjustment willpermitthe operator to so control the apparatus a as to effectively maintain the 10 angle in a sea that tends to rollthe vessel at'a greater angle.

times exist when it-is desired toroll the On war vessels a condition may: some vessel to the desired angle ofelevation of' p the guns and maintain that maximum elevation for a short period of time to give suflicient pause in the roll to'permit'the'gun to be accurately fired. Electromagnets 104: and 105 on the pendulum switch bar 25 are provided for this purpose and their :energization is eontroll'ed; by switches or push buttons 106 -and 107 Let it be assumed that the stabilizer is rolling the vessel in" a smooth ora moder'ate sea'to some high angle: desired by the gunners and it is also desired to holdthe maximum roll topere 111113311116 gunners to fire with greaterac'curacy. Again, let it be assumed-that the vesa sel isfrolling in such direction as to'bring contact 28 into engagement with contact: 29 oIl-the pendulum switch 'ba'r25. A- short time before the vessel reaches the maximum roll the push button or switch 106 is pressed to bring the contacts .into engagement.

This energizes coil 104: by current coming from main L3, coil91, conductor'109, coils 105. and 10 1, push button106-and-wire 97 I back to main L4. This energizes these coils andholds contacts 28 and. 29 togetherby action of armature 68 positioned-on switch bar. 23. Whenth-evessel starts the return roll contacts 28 and 29 are notopen as would normally be the. case because of this action of magnets v10 1'and 105. The circuitgof regulating coil 44 is therefore not open at.

the V pendulum switch points dynamo electric machines '1 and 2 continue their stabilizing action and maintain the vessel in the desired angle of roll for a short period of time to enable the guns to be fired. This push button will be maintained closed only. for a short period of time. To steady the movement of pendulum 26 I may use a damping arrangement such as an electromagnet 110 positioned adjacent to a copper or other metallic strip 111 attached to the base of-the pendulum Weight. This magnet is connected to main L3 through resistance 108 and to main L4 through wire 97. Eddy currents will be induced in the copper strip 111 when it is moved through the field of the magnet 110 in the well known way. Sudden movement will be re tarded by this eddy current action to a greater extent than slow movements.

-The flywheels and associated devices will be designed so that the energy absorbed by acceleration of one fiywheelwill practically equal the energy given out by the retarded flywheel.v Under such conditions the cu rent taken from the means L1 and L2 will be that required to make up the losses in the V dynamo electric machines and loss of energy due to rolling of machine. Therefore, there will be practically no undue surges of current into and out of these means.

and to dampen them out I may place a battery acrossthe mains by closing switch SB to absorb the excess of energy coming from by themains. -However, in most cases the use of the battery and damping device would. be unnecessary.

Having described my. invention, what I claim is: I

1'. The method of stabilizing an "oscillating object which consists in rotating two flywheels in opposite directions in'planes that are parallel to the plane of oscillation, applying forceto retard one flywheel and accelerate the other to produce reaction forces in opposition to the forces of oscillation and maintaining. said applied forces substantially constant. as the amplitude of oscillation. increases.

2. The method of stabilizing an oscillating object which consists in rotating two flywheels in opposite directionsv in planes that are parallel to the plane of oscillation,

applying force to retard one. flywheel and acceleratethe other to.- produce reaction How- 7 ever, 1n some cases there may besuch surges forces in opposition to the force of oscillation and regulating the application of said applied force independently of the angle taken by theobject.

3. The method of stablizing an oscillating object which consists in rotating two flywheels in opposite directions in planes that are parallel to the plane of oscillation, applying force to retard one flywheel and accelerate the other to produce reaction forces in opposition to the forces of oscillation, and regulating the application of said applied forces to each flywheel independently of the other.

4:. The method of oscillating an object which consists in rotating two flywheels in oppositedirections in planes that are parallel to the desired direction of oscillation,

applying force to retard one flywheel and accelerating the other to produce reaction forces on the ob ect in the desired direction of oscillation, and reversing the force applied to said flywheels when the object has reached a predetermined amplitude of oscillation.

5. The method of oscillating an object which consists in rotating two flywheels in opposite directions in planes that are parallel to the desired direction of oscillation, applying forces to retard one flywheel and accelerate the other to produce reaction forces'on said object in the desired direction of oscillation, maintaining said forces substantially constant and reversing the forces applied to said flywheels when the object has reached a predetermined amplitude of oscillation.

6. The method of oscillating an object which consists in rotating two flywheels in opposite directions in planes that are parallel to the desired direction of oscillation, applying force to retard one flywheel and accelerate the other and maintaining the application of forces to said flywheels when maximum amplitude has been reached to delay the oscillation of the object at such amplitude.

' 7.. In devices forcontrolling oscillations of an object, two dynamo electric machines having stationary members attached to said object and rotary members rotating in opposite directions in planes parallel to the plane of oscillation, one of said members in each machine being electrically connected to the source of current supply and to the member of the other machine, and means for maintaining one machine as a generator and the other as a motor during one portion of the cycle and for maintaining the former as a motor and the latter as a'generator during another portion of the cycle.

8. In devices for controlling oscillations of an object, two dynamo electric machines armatures rotating in opposite directions in planes parallel to the plane of oscillation the object to strengthen the electrical field of one of said machines and weakening that of the other. r r

9. In devices for controlling oscillations of a vessel, two dynamo electric machines supported on said vessel and having their armatures electrically connected in parallel across the supply mains, flywheels associated with the machine and rotated thereby in opposite directions in planes that are parallel to the plane of oscillation, and means controlled by the oscillation of the vessel to weaken the electrical field of one" machine and strengthon that of the other. 7

10. In devices for controlling oscillations of a vessel, two dynamo electric machines supported on said vessel and having armatures electrically connected in parallel across the source of current supply, flywheels associated with armatures and rotated in directions opposite to each other in planes that are parallel to the direction of oscillation, means controlled by the oscillation of the vesselto weaken the electrical field ofone' machine-and strengthen that of the other, and means for controlling at.;-will thevalue of said electrical fields;-

'11. In devices for controlling oscillations of a'vessel, two dynamo felectricmachines '5 supportedon said vessel and having armatures connected in parallel across the source of current supply, flywheels associatedwith the armatures and rotated in directions opposite to each other in planesthat are" par allel to the direction of oscillation of the vesnetic devices, a reversing switch, additional sel, means controlled by the saidoscillations to weaken the electrical field of one machine and strengthen that of the other, and means for maintaining the reaction between said machines and the vessel substantially con v stant during a portion or the "oscillatio'nma 12. In devices for controlling oscillations of a vessel, two dynamo electric machines supported on said vessel'and having their armatures rotating in opposite directions in planes parallel to the plane of the oscillations, rotatable masses connected to the armatures, a device adapted to maintain a substantially unvarying position during the oscillating cycle, contacts on said device, contacts adapted to move with the oscillating vessel, electromagnetic devices connected to said contacts and adapted to reversely vary the field currents of said machines to retard one of said masses and accelerate the other.

13. In devices for controlling oscillations of a vessel, two dynamo electric machines supported on said vessel and having their armatures rotating in oppositedirection in planes parallelto the plane of the oscilla- 16. In devices tion supply," rotatable masseslconnected .to the armatures, aresistance in the field cir rotatable masses connected to the armatures,

a resistance in the field circuit of each machlne, electromagnetic devices for short -c1rcuiting said resistance, a contact connectedto' each of said electromagnetic devices, and means adapted to connect the source of current supply alternately to said contacts.

15. In devices for controlling oscillations of a vessel, two dynamo electric machines supported on said vessel and'having their armatures rotating in opposite directions in planes that are parallel to the plane of the oscillations and electrically connected; to the sources of current supply and'to each other whereby" the said current'supply operates said machines-as motors and the excess 'current from the armature of oneflnachin'e feeds current'to the armature :of theother machine, rotatable' masses, connectedfto the I fieldof each -machine, means for short-circuiting said resistances alternately, stationary contacts, movable with the vessel adapt ed toengage said stationarycontacts, said a armatures, a resistance in the circuit of the contacts being connected to said electromagcontactsadap'ted to be 'brought'together by movement of'the vessel in its oscillating plane to operate said reversing switch-and remove the short-circuit around the first re sistance and place a short-circuit around the second resistance. l

for controlling oscillations V of azvessel, two dynamo electricmachines supported on said vessel and having their planes that are parallel'tothe plane of the oscillation, rotatable masses connected to said armatures to impose equaland oppo- ,armatures rotating in opposite directions in site reactions on said vessel when both said a machines are operating as motors, contacts adapted to be closed by the oscillations of the vessel to convert one of the machines intova generator to produce a reaction with the other machine in opposition to the movement of the vessel, additional contactshadapted to be closed on further oscillation of the vessel to convert the first machine into a motor and the other into a generatorbefore dition of the machines for a predetermined time after thevessel tends to make a return cycle. I

18. In devices for controlling oscillations of a vessel two dynamo electric machines supported on said vessel and having their armatures rotating in opposite directions in planes that are parallel to the plane of the oscillation, rotatable masses connected to the armatures, means for maintaining one of said machines as a generator and the other as a motor during the major portion of a cycle, and means for converting said motor into a generator and said generator into a motor before the maximum position in the oscillating cycle is reached.

19. In devices for controlling oscillation of a vessel two dynamo electric machines supported on said vessel and having their armatures rotating in opposite directions in planes that are parallel to the plane otthe os'cillation,rotatable masses connected to the armatures, means for maintaining one of said machines as a generator and the other as a motor during the major portion of a cycle, and means for converting said motor 1nto a generator and said generator into a motor before the maxlmum position 1n the oscillating cycle is reached, and means for reducing the maximum field strength of said machines for one or more cycles.

20. In direct current machines, a rotatable armature, a field coil for producing magnetic flux through said armature, means for increasing current in said field coil and a short circuited coil positioned to oppose sudden changes in magnetic flux produced by said field ,coil to minimize inductive effects caused by such sudden changes.

I 21. In direct current machines, a rotatable armature, a field core, a field coil for producing magnetic flux in said core and armature, a resistance in circuit with said field coil, means for varying said resistance and a short-circuited coil on said core to oppose sudden changes in said magnetic flux. i 22. In devices for controlling oscillations of an object, two dynamo electric machines having armatures rotating in opposite 'directions in planes parallel to the plane of oscillations, field coils for producing magnetic flux through said armatures, resistances in circuit with said field coils, means for varying said resistances to maintain one machine as a generator and the other as a motor during one portion of a cycle and for maintaining the former as a motor and the latter as a generator during another portion of the cycle and short-circuited coils positioned to opposesudden changes in the magnetic flux produced by said field coils.

28. The method of stabilizing an oscillating object which consists in rotating two flywheels in opposite directions in planes that are parallel to the plane of oscillation, retarding during one part of the cycle one flywheel, using all the energy of retardation, except for the losses, to speed up the other, retarding during another part of the cycle the second mentioned flywheel, using the energy of retardation, except for the losses, to speed up the first mentioned flywheel and supplying the losses from another source.

24. The method of stabilizing an oscillating object which consists in connecting together the armatures of two dynamo electric machines rotating in opposite directions, causing one to operate as a generator and the other as a motor, and supplying current to said machine only to the extent necessary to make up the losses;

25. In devices for controlling oscillations of an object, t wo dynamo electric machines having stationary members attached to said object and rotarymembers rotating in opposite directions in planes parallel to the plane of oscillation, means for maintaining one machine as a generator, and the other as a .motor during one portion of the cycle, and

the former. as a motor and the latter as a generator during another portion of the cycle, means for causing the load of the generator to be absorbed by the motor except for the losses and another source for supplying the losses.

In testimony whereof, I have signed my name to this specification this 11th day of November 1929. PERRY B. SAMPLE. 

